Can't really comment on the Celestron power tanks, but the only negatives I have really seen on this form of power is that they sometimes give out at the wrong time.I know the one I have had for a couple of years ( Senco ) just died on me so I am now in the process of building my own, the plans are on the CN website by the way.

The big plus I can see with building my own is that I can have as many of the cigarette plugs as I want, as long as I don't draw anymore power than the battery is designed to for.

I know others will add in the choices plus pro's and con's of different units.

I have both the 7 amp hour Celestron tank and the 17. I have never been able to charge the 17 up to the 13+ volts it should take. No such problem with the 7. I use the 7 to run the go-to, since the computer goes crazy if the voltage gets too low, and the 17 to run the dew tape. Tried to run both on the 17, but after a bit the go-to went whacko from low voltage.Just one data point.Clear skies,Nicholas

I have skywatcher 17Ah power tank which as far as i know is the same as the celestron. I use it to power my heq5 mount with 8" f5 reflector and did not have any problems with it. My mount is not goto. I have used it for about 5 hours maximum and i have not measured the voltage of the power tank so can not tell if it is full 17Ah or not.

The Celestron/Orion/Skywatcher, et al., are pretty expensive choices for what they provide. I've had mine for about three years, and up until this weekend it behaved very well. However, I didn't get the duration this weekend that I should have, and I'm afraid it's on its way out.

Some precautionary words are in order. First, the "wall wart" charger works at about .8 amps. That means that, God Forbid, you took the tank way down, you are looking at 20 hours or more to recharge. Do NOT believe the lights on the side of the unit during recharge; at least, do not believe them literally. The "Ready" light will come on and make you think it is fully charged. Nope. It only means it has enough juice to squeeze out 12V. But a 12V battery such as the one used for this purpose should be well over 13V at full charge. You MUST let this one go until the "Charging" light goes out as well. The good news is that the wall wart pushes a nominal 15V, which is good enough to fully charge the unit. Some others only provide a 12V output wall wart, which is not enough oomph to fully charge it and these batteries WILL fail if they are not kept as close to fully charged as possible when not in use. And more than about 50% draw down very often will kill the batteries as well, unless they are deep dishcarge marine type batteries.

Finally, the wall warts have a bad reputation as well since they seem to die early, and don't have overcharge protection when they work. I use a battery defender type unit, which does a quick charge at 3 amps, then tops it off at 13.5V, then holds the full charge at 0 amps to protect the system. If you use this type of charging/maintenance device, do not use the 12V input point; connect directly to the starter cables. This will charge the battery quickly and maintain the charge safely.

I need a portable power source for my new CGEM and seem to reading a number of negative comments on this portable power source. Can someone clue me in...Thank You!

Come si, come sa. Some folks have had good luck with it. Some have not. Bottom line? Why pay more for one that says "Celestron" (or Orion, or whatever) on it when you can trot down to Walmart and get one with more capacity which is possibly more reliable for the same money or LESS?

However many owners reported that the red/Charging light never goes out. I have never seen it going out on my 7Ah either no matter how many days I was charging.

Maybe this is due to the poor reliability in the wall chargers? There have been many reports in the Equipment forum over the years on this same topic, and the wall chargers that come with them seem to be really a problem with some lasting less than four or five uses.

Mine has performed very well over the years, with about four or five heavy uses per month for three years. But the more these threads pop up, the luckier I feel!

Uncle Rod is right. There are wiser choices out there. Check the Equipment forum going back a year or two; the topic of power supplies in general and the Power Tanks in particular is a recurring theme, with a lot of great alternatives. Wish I knew then what I know now!

I'm one of the folks that had issues relatively quickly with two separate units. While I'm well aware that some people have had years of use out of their units with no issues, it seems just as many have had problems. The chance you take is having to ship it to California if you have an issue. Depending where you live, the cost of shipping can easily be as much as the 17 aH Husky unit that Home Depot sells. For the same price as the astronomy branded unit, you can get a 22 aH version from Sears with more features and a built in trickle charger. To me, it just makes more sense to shop around town a little. You'll probably end up with a less expensive unit or one with more features (or both). And if there's a problem, you don't have to pay for shipping to return it.

I've had the Orion version, which is the exact same unit as the Celestron, going on two years and it continues to work flawlessly. FYI Orion no longer carries the 17 amp version. I even used it to jump start the battery on my wife's car. Worked like a charm.

I was told by a member of CN that the best way to ensure longevity is to always charge it after each use, but not to exceed more than 12 hours.

Lead-acid batteries, and that includes all of the 12V gel-cell and AGM types used as "power tanks" for astronomy equipment, as well as auto batteries and deep cycle batteries, are damaged by being discharged too deeply, by remaining discharged for extended periods, and by heat.

So the best way to ensure longevity is to buy a battery with enough capacity so that you don't have to discharge it too deeply, keep it charged whenever it is not in use, and not overcharge it.

How deeply a battery can be discharged without excessive damage depends on the type of lead electrodes it has. Deep cycle batteries have dense, solid lead electrodes, while automobile batteries have spongey lead electrodes. Marine batteries and other types that are usually labelled "deep cycle" are actually hybrids, having denser electrodes than automobile batteries but not solid lead electrodes. The trade off for solid lead electrodes is obviously more weight, and also less instantaneous current capacity. Spongey lead electrodes like the ones used in automobile batteries can supply very large amounts of current for short periods, but are easily damaged by deep discharge.

In order to keep a battery fully charged while not in use but avoid overcharging, the "float charger" is the best choice. Instead of constantly feeding current into the battery (as happens with some brute force chargers and some "trickle chargers"), it maintains a constant voltage (usually around 13.2 to 13.5 volts), and the battery only draws current when needed to maintain that voltage. So you can keep the battery hooked up to the float charger all the time when it is not in use, preventing the harmful self discharge that will eventually ruin a battery that is left unused and uncharged for long periods.

I have had my battery for 6 months and it works flawlessly, but remember that these batteries are generally only good for 200 charges, so lets say I take out the scopes 2 x a week, I have charged the battery 52 times, which means I am already at 25% of the battery life. And I used it in 5-10 degrees which degrades battery life more. If the battery lasts longer than 2 years I will be happy. Look at any extra life after 2 years as a bonus.

I bought the Orion version several years ago and it lasted about six months before it quit taking a charge. At the time, I was only charging it when the recharge light came on - the instructions that came with it were very vague on when to recharge. I returned it to the dealer and got a replacement which came with an addendum to the instructions stating that it had to be charged at least once a month. Since then, I've had no problem with it, so obviously that's the secret to making it last.

I bought an awesome battery at Home Depot for about a hundred dollars or hundred twenty. It has the cigarette plugs but can also have the ability to jump a car. I never had to charge it the whole time at TSP. I believe it is a black and decker brand.

I have the small powertank that Celestron sells too, it is ok. It will power my Nexstar for a few hours, so it is nice when I am at the house.

Like with Celestron and Orion powertanks, the real manufacturer might be a different company. www.xantrex.com is one of powertank suppliers to Black & Decker. It really gets confusing who makes what these days.

I had a couple of different power supplies. I never used one specifically made for astronomy. I tried a black and decker. it died without doing much. turned it in for another, and that one died. I tried one of them that sells in pilot truck stops. It died too. I got my money back and was wandering in wally world one day, an I said to myself "self... If ya want power, git sumpin made to hold a LOT of power". I picked up a lawntractor battery ($20) and a smart charger ($30), and never looked back. that has been two years ago. I have never come anywhere near draining it. although I dont have any dewkillers, I think it would run these as well for a whole night. It sets sometimes for 2 months at a time, without recharge ready for use in the instant. I use it, then put it on charge to find out that it does not need that much charging anyway. I think they are the biggest bang for the buck. I built a little box for it with a handle. these are less than half the size of a standard car battery. yeah , they dont have all the little do-dads on them (that are usually pretty useless anyway), but who needs xtra lights, calculators , computers, an all this other garbage that aint worth a flip anyway? I built my little box, and put a lighter socket on it, and I am good to go.

oh yeah, I fergot to add that in... the battery can be used for many other things too. jumping motorcycles off, (done that ) powering portable air pumps, even powering hair dryers (warm not hot, depending on size of inverter) to kill the dew. the possibilities are endless! lets see you do that with a flimsy little powertank. Ha! NOT!